Heat stable photocurable resin composition for dry film resist

ABSTRACT

The invention relates to a process for preparing a dry film resist by forming a photocurable resin composition onto a support film with a thickness of 1 to 50 μm and optionally laminate a protective film onto the photocurable composition layer to obtain a dry film resist; whereby the photocurable resin is formed from a homogeneous mixture comprising (a) from 20–90 wt % of an alkaline soluble binder oligomer or polymer; (b) from 5 to 60 wt % of one or more photopolymerizable monomers which are compatible with the oligomers and polymers of component (a); (c) from 0.01 to 20% by weight of one or more photoinitiators; (d) from 0 to 20% by weight of additives and/or assistants; and (e) from 0.1 to 10% by weight of a leuco triphenylmethane dye of the formula (I), wherein R 1  is a residue selected from (II), R 2  is C 1 –C 12  alkyl or phenyl which may be mono-, di- or tri-substituted by C 1 –C 6  alkyl, trifluoromethyl, C 1-6  alkoxy, C 1-6  alkylthio, halogen and nitro; R 3  is hydrogen or C 1 –C 12  alkyl; R 4  to R 9  independently of one another are hydrogen or C 1 –C 12  alkyl; X is O, S, NH or N—C 1 –C 12 -alkyl; (a) to (e) being 100% by weight. The above composition is useful to avoid unfavourable colour generation during the heat lamination

The present invention relates to heat stable photocurable resincomposition and to the use of this composition as a photosensitive layerfor a dry film resist.

The so-called “dry film resists” are three-ply films which are producedby sandwiching a photocurable resin composition layer between a supportfilm and a protective film. The photocurable resin composition isusually an alkali developing type. The unexposed portions are removedwith an aqueous alkali solution upon development.

The photosensitive layer of dry film resists includes color formers thatgenerate color after UV exposure and let the worker easily recognize ifthe resist is already exposed. Typically leuco crystal violet or leucomalachite green has been used as the color former for a dry film resist.Because their thermal stability is not sufficient, color is generatedwhile thermally laminating the photocurable resin composition onto asubstrate. This undesired color generation during the lamination processreduces the color contrast between exposed and unexposed area.

Thus, it is an object of the invention to reduce the undesired colorgeneration during heat lamination process and get a clear color contrastbetween exposed and unexposed area.

It has now been found that the unfavourable color generation during theheat lamination process is minimized when using a leuco dye as describedbelow.

Thus, the invention relates to a process for preparing a dry film resistby forming a photocurable resin composition onto a support film with athickness of 1 to 50 μm and optionally laminate a protective film ontothe photocurable composition layer to obtain a dry film resist; wherebythe photocurable resin is formed from a homogeneous mixture comprising

-   (a) from 20–90 wt % of an alkaline soluble binder oligomer or    polymer;-   (b) from 5 to 60 wt % of one or more photopolymerizable monomers    which are compatible with the oligomers and polymers of component    (a);-   (c) from 0.01 to 20% by weight of one or more photoinitiators;-   (d) from 0 to 20% by weight of additives and/or assistants; and-   (e) from 0.1 to 10% by weight of a leuco triphenylmethane dye of the    formula I

wherein

-   R¹ is a residue selected from

-   R² is C₁–C₁₂ alkyl or phenyl which may be mono-, di- or    tri-substituted by C₁–C₆ alkyl, trifluoromethyl, C₁₋₆ alkoxy, C₁₋₆    alkylthio, halogen and nitro;-   R³ is hydrogen or C₁–C₁₂ alkyl;-   R⁴ to R⁹ independently of one another are hydrogen or C₁–C₁₂ alkyl;-   X is O, S, NH or N—C₁–C₁₂-alkyl;-   (a) to (e) being 100% by weight.

Preferred are leuco triphenylmethane dyes of the formula I, wherein

-   R¹ is a residue selected from

-   R² is unsubstituted phenyl,-   R³ is C₁–C₄alkyl-   R⁴ is hydrogen;-   R⁵ and R⁷ are C₁–C₄alkyl.

Especially preferred is4,4′-[(9-Butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenyl-aniline]as a color former (Pergascript Blue S-RBP from Ciba SpecialtyChemicals).

Preferred is the lamination of a protective film onto the photocurablecomposition layer.

Definitions:

In the definitions of the respective groups in the general formula (I),the C₁–C₁₂alkyl and the alkyl moiety in the C₁–C₆ alkoxy or alkylthiomeans a straight or branched alkyl having 1 to 12 carbon atoms, forexample, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl,tert-butyl, pentyl, neopentyl, hexyl, etc.

Component (a) is an Alkaline Soluble Binder Polymer.

The suitable binders are polymers having a molecular weight of about2'000 to 2'000'000, preferably 10,000 to 500'000, and acid value from 50to 600 mgKOH/g, preferably 100 to 300 mgKOH/g. Examples of alkalidevelopable binders are acrylic polymer having carboxylic acid functionas a pendant group, such as conventionally known copolymers obtained bycopolymerizing an ethylenic unsaturated carboxylic acid such as(meth)acrylic acid, 2-carboxyethyl (meth)acrylic acid, 2-carboxypropyl(meth)acrylic acid itaconic acid, crotonic acid, maleic acid, half-esterof maleic acid and fumaric acid, with one or more monomers selected fromesters of (meth)-acrylic acid, such as methyl (meth)acrylate, ethyl(meth)acrylate, propyl (meth)-acrylate, butyl (meth)acrylate, benzyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)C₁–C₄alkyl acrylate, hydroxypropyl (meth)acrylate; vinyl aromaticcompounds, such as styrene, α-methylstyrene, vinyltoluene,p-chlorostyrene; amide type unsaturated compounds, (meth)acrylamidediacetone acrylamide, N-methylolacrylamide, N-butoxymethacrylamide; andpolyolefin type compounds, such as butadiene, isoprene, chloroprene andthe like; methacrylonitrile, methyl isopropenyl ketone, vinyl acetate,vinyl propionate, or vinyl pivalate. Examples of copolymers arecopolymers of acrylates and methacrylates with acrylic acid ormethacrylic acid and with styrene or substituted styrene, phenolicresins, for example novolak, (poly)hydroxystyrene, and copolymers ofhydroxystyrene with alkyl acrylates, acrylic acid and/or methacrylicacid. Preferable examples of copolymers are copolymers of methylmethacrylate/methacrylic acid, copolymers of benzylmethacrylate/methacrylic acid, copolymers of methyl methacrylate/ethylacrylate/methacrylic acid, copolymers of benzyl methacrylate/methacrylicacid/styrene, copolymers of benzyl methacrylate/methacrylicacid/hydroxyethyl methacrylate, copolymers of methyl methacrylate/butylmethacrylate/methacrylic acid/styrene, copolymers of methylmethacrylate/benzyl methacrylate/methacrylic acid/hydroxyphenylmethacrylate. The polyimide binder resin in the present invention can bea polyimide precursor, for example, a poly(amic acid).

Other examples of component (a) are polymers or oligomers having atleast two ethylenically unsaturated groups and at least one carboxylfunction within the molecule structure, such as a resin obtained by thereaction of a saturated or unsaturated polybasic acid anhydride with aproduct of the reaction of an epoxy compound and an unsaturatedmonocarboxylic acid (for example, EB9696 from UCB Chemicals; KAYARADTCR1025 from Nippon Kayaku Co. LTD.; NK OLI GO EA-6340, EA-7440 fromShin-Nakamura Chemical Co., Ltd.), or an addition product formed betweena carboxyl group-containing resin and an unsaturated compound having anα,β-unsaturated double bond and an epoxy group (for ex., ACA200,ACA200M, ACA210P, ACA230AA, ACA250, ACA300, ACA320 from Daicel ChemicalIndustries, Ltd.).

Examples of component (b) which are suitable in the compositionsaccording to the invention are photopolymerizable vinyl type monomers.The representative examples are hydroxyalkyl acrylates such as2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, etc.; mono- ordiacrylates of glycols such as ethylene glycol, methoxytetraethyleneglycol, polyethylene glycol, propylene glycol, etc.; acrylamides such asN,N-dimethylacrylamide, N-methylolacrylamide, etc.; aminoalkyl acrylatessuch as N,N-dimethylaminoethyl acrylate, etc.; polyvalent acrylates ofpolyvalent alcohols such as hexanediol, trimethylolpropane,pentaerythritol, dipentaerythritol, and ethylene oxide or propyleneoxide adducts thereof, tris-hydroxyethyl isocyanurate, etc.; phenoxyacrylate, bisphenol A diacrylate and acrylates of ethylene oxide orpropylene oxide adducts of these phenols, etc.; acrylates of glycidylethers such as glycerin diglycidyl ether, trimethylolpropane triglycidylether, triglycidyl isocyanurate, etc.; and melamine acrylate, and/ormethacrylates corresponding to the above acrylates, etc.

A mono- or multi-functional ethylenically unsaturated compound, ormixtures of several of said compounds, can be included in the abovecomposition up to 60% by weight based on the solid portion of thecomposition.

The unsaturated compounds (b) can also be used as a mixture withnon-photopolymerizable, film-forming components. These may, for example,be physically drying polymers or solutions thereof in organic solvents,for instance nitrocellulose or cellulose acetobutyrate. They may also,however, be chemically and/or thermally curable (heat-curable) resins,examples being polyisocyanates, polyepoxides and melamine resins, aswell as polyimide precursors. The use of heat-curable resins at the sametime is important for use in systems known as hybrid systems, which in afirst stage are photopolymerized and in a second stage are crosslinkedby means of thermal after treatment.

Any compound so far known as a photoinitiator can be used as a component(c). The examples of component (c) are camphor quinone, benzophenone,benzophenone derivatives, acetophenone, acetophenone derivatives, forexample α-hydroxycycloalkyl phenyl ketones or2-hydroxy-2-methyl-1-phenyl-propanone, dialkoxyacetophenones, α-hydroxy-or α-aminoacetophenones, e.g.(4-methylthiobenzoyl)-1-methyl-1-morpholinoethane,(4-morpholinobenzoyl)-1-benzyl-1-dimethylaminopropane,4-aroyl-1,3-dioxolanes, benzoin alkyl ethers and benzil ketals, e.g.dimethyl benzil ketal, phenylglyoxalic esters and derivatives thereof,dimeric phenylglyoxalic esters, diacetyl, peresters, e.g. benzophenonetetracarboxylic peresters as described for example in EP 126541,monoacyl phosphine oxides, e.g.(2,4,6-trimethylbenzoyl)diphenylphosphine oxide, bisacylphosphineoxides, bis(2,6-dimethoxy-benzoyl)-(2,4,4-trimethyl-pentyl)phosphineoxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide,bis(2,4,6-trimethylbenzoyl)-2,4-dipentoxyphenylphosphine oxide,trisacylphosphine oxides, oxime esters, for example1-phenyl-1,2-propanedione-2-(o-benzoyl)oxime,1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime or other oximeesters described in GB2339571A and U.S. 2001/0012596A1,halomethyltriazines, e.g.2-[2-(4-methoxy-phenyl)-vinyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-(4-methoxy-phenyl)-4,6-bis-trichloromethyl-[1,3,5]triazine,2-(3,4-dimethoxy-phenyl)-4,6-bis-trichloromethyl-[1,3,5]triazine,2-methyl-4,6-bis-trichloromethyl-[1,3,5]triazine,2-(4-N,N-di(ethoxycarbonylmethyl)-aminophenyl)-4,6-bis(trichloromethyl)-[1,3,5]triazine,2-(4-methoxy-naphthyl)-4,6-bis-trichloromethyl-[1,3,5]triazine,2-(1,3-benzodioxol-5-yl)-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[2-[4-(pentyloxy)phenyl]ethenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[2-(3-methyl-2-furanyl)-ethenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[2-(5-methyl-2-furanyl)-ethenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[2-(2,4-dimethoxy-phenyl)-ethenyl]-4,6-bis-trichloromethyl[1,3,5]triazine,2-[2-(2-methoxy-phenyl)ethenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[2-[4-isopropyloxy-phenyl]-ethenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[2-(3-chloro-4-methoxy-phenyl)ethenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[2-bromo-4-N,N-di(ethoxycarbonylmethyl)amino-phenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[2-chloro-4-N,N-di(ethoxycarbonylmethyl)amino-phenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[3-bromo-4-N,N-di(ethoxycarbonylmethyl)amino-phenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,2-[3-chloro-4-N,N-di(ethoxycarbonylmethyl)amino-phenyl]-4,6-bis-trichloromethyl-[1,3,5]triazine,or other halomethyl-triazines as described for example in G. Buhr, R.Dammel and C. Lindley Polym. Mater. Sci. Eng. 61, 269 (1989), and EP0262788; halomethyl-oxazol photoinitiators, such as described in U.S.Pat. No. 4,371,606 and U.S. Pat. No. 4,371,607; 1,2-disulfones, such asdescribed in E. A. Bartmann, Synthesis 5, 490 (1993);hexaarylbisimidazole, and hexaarylbisimidazole/coinitiators systems,e.g. ortho-chlorohexaphenyl-bisimidazole combined with2-mercaptobenzthiazole, ferrocenium compounds, or titanocenes, e.g.bis(cyclopentadienyl)-bis(2,6-difluoro-3-pyrryl-phenyl)titanium,bisacridine derivatives like 1,7-bis(9-acridinyl)heptane. One of thementioned photoinitiators, or mixtures of several said compounds, can beincluded in the above composition up to 20% by weight based on the solidportion of the composition.

Further additives (d) which may be included. To promote the colorformation of the triphenylmethane dye e) it is possible to addhalogenated compounds, triazines,-bisimidazoles or onium salt type photoacid generators as an example of component d). The examples of thehalogenated compounds are amyl bromide, isoamyl bromide, isobutylbromide, ethyl bromide, diphenylmethyl bromide, benzoyl bromide,methylene bromide, tribromomethylphenylsulfone, tribromophenylsulfone,carbon tetrabromide, tris(2,3-dibromopropyl)phosphate, pentabromoethane,trichloroacetamide, amyl iodide, isobutyl iodide,1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane and hexachloroethane. Theexamples of onium salt type photo acid generators are bisaryl iodoniumcompounds and triaryl sulfonium compounds. Suitable diaryliodonium saltsare described in U.S. Pat. No. 6,306,555. U.S. Pat. No. 6,306,555describes diaryliodonium salts of formula

wherein

-   X is branched C₃–C₂₀alkyl or C₃–C₈cycloalkyl;-   X₁ is hydrogen, linear C₁–C₂₀alkyl, branched C₃–C₂₀alkyl or    C₃–C₈cycloalkyl; with the proviso that the sum of the carbon atoms    in X and X₁ is at least 4;-   Y is linear C₁–C₁₀alkyl, branched C₃–C₁₀alkyl or C₃–C₈cycloalkyl;-   A⁻ is a non-nucleophilic anion, selected from the group (BF₄)⁻,    (SbF₆)⁻, (PF₆)⁻, (B(C₆F₅))₄ ⁻, C₁–C₂₀alkylsulfonate,    C₂–C₂₀haloalkylsulfonate, unsubstituted C₆–C₁₀arylsulfonate,    camphorsulfonate, C₁–C₂₀-perfluoroalkylsulfonylmethide,    C₁–C₂₀-perfluoroalkylsulfonylimide, and C₆–C₁₀arylsulfonate    substituted by halogen, NO₂, C₁–C₁₂alkyl, C₁–C₁₂halo-alkyl,    C₁–C₁₂alkoxy or by COOR₁; and-   R₁ is C₁–C₂₀alkyl, phenyl, benzyl; or phenyl mono- or    poly-substituted by C₁–C₁₂alkyl, C₁–C₁₂alkoxy or by halogen.

The commercially available bisaryl iodonium salts are Irgacure 250(iodonium, (4-methylphenyl)[4-(2-methylpropyl)phenyl]-,hexafluorophosphate(1−) from Ciba Specialty Chemicals), CD 1012(Sartomer), UV 9380C (GE Bayer Silicones), Rhodorsil 2074 (Rhodia) etc,and triaryl sulfonium salts are UVI-6990, UVI-6974 (Union Carbide) etc.

It is possible to add photosensitizers or coinitiators to accelerate thephoto curing speed as an example of component (d) which shift or broadenthe spectral sensitivity. These are, in particular, aromatic compounds,for example benzophenone and derivatives thereof, thioxanthone andderivatives thereof, anthraquinone and derivatives thereof, coumarin andphenothiazine and derivatives thereof, and also3-(aroylmethylene)thiazolines, rhodanine, camphorquinone, but alsoeosine, rhodamine, erythrosine, xanthene, thioxanthene, acridine, e.g.9-phenylacridine, 1,7-bis(9-acridinyl)heptane,1,5-bis(9-acridinyl)pentane, cyanine and merocyanine dyes.

Specific examples of such compounds are

1. Thioxanthones

Thioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone,1-chloro-4-propoxythioxanthone, 2-dodecylthioxanthone,2,4-diethylthioxanthone, 2,4-dimethylthioxanthone,1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone,3-(2-methoxyethoxycarbonyl)-thioxanthone, 4butoxycarbonylthioxanthone,3-butoxycarbonyl-7-methylthioxanthone, 1-cyano-3-chlorothioxanthone,1-ethoxycarbonyl-3-chlorothioxanthone,1-ethoxycarbonyl-3-ethoxythioxanthone,1-ethoxycarbonyl-3-aminothioxanthone,1-ethoxycarbonyl-3-phenylsulfurylthioxanthone,3,4-di-[2-(2-methoxyethoxy)ethoxycarbonyl]-thioxanthone,1,3-dimethyl-2-hydroxy-9H-thioxanthen-9-one 2-ethylhexylether,1-ethoxycarbonyl-3-(1-methyl-1-morpholinoethyl)-thioxanthone,2-methyl-6-dimethoxymethyl-thioxanthone,2-methyl-6-(1,1-dimethoxybenzyl)-thioxanthone,2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone,N-allylthioxanthone-3,4-dicarboximide,N-octylthioxanthone-3,4-dicarboximide,N-(1,1,3,3-tetramethylbutyl)-thioxanthone-3,4-dicarboximide,1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone,6-ethoxycarbonyl-2-methylthioxanthone, thioxanthone-2-carboxylic acidpolyethyleneglycol ester,2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthon-2-yloxy)-N,N,N-trimethyl-1-propanaminiumchloride;

2. Benzophenones

benzophenone, 4-phenyl benzophenone, 4-methoxy benzophenone,4,4′-dimethoxy benzophenone, 4,4′-dimethyl benzophenone,4,4′-dichlorobenzophenone 4,4′-bis(dimethylamino)benzophenone,4,4′-bis(diethylamino)benzophenone,4,4′-bis(methylethylamino)benzophenone,4,4′-bis(p-isopropylphenoxy)benzophenone, 4-methyl benzophenone,2,4,6-trimethylbenzophenone, 4-(4-methylthiophenyl)-benzophenone,3,3′-dimethyl-4-methoxy benzophenone, methyl-2-benzoylbenzoate,4-(2-hydroxyethylthio)-benzophenone, 4-(4-tolylthio)benzophenone,1-[4-(4-benzoy-phenylsulfanyl)-phenyl]-2-methyl-2-(toluene-4-sulfonyl)-propan-1-one,4-benzoyl-N,N,N-trimethylbenzenemethanaminium chloride,2-hydroxy-3-(4-benzoylphenoxy)-N,N,N-trimethyl-1-propanaminium chloridemonohydrate, 4-(13-acryloyl-1,4,7,10,13-pentaoxatridecyl)-benzophenone,4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyl)oxy]ethyl-benzenemethanaminiumchloride;

3. Coumarins

Coumarin 1, Coumarin 2, Coumarin 6, Coumarin 7, Coumarin 30, Coumarin102, Coumarin 106, Coumarin 138, Coumarin 152, Coumarin 153, Coumarin307, Coumarin 314, Coumarin 314T, Coumarin 334, Coumarin 337, Coumarin500,3-benzoyl coumarin, 3-benzoyl-7-methoxycoumarin,3-benzoyl-5,7-dimethoxycoumarin, 3-benzoyl-5,7-dipropoxycoumarin,3-benzoyl-6,8-dichlorocoumarin, 3-benzoyl-6-chloro-coumarin,3,3′-carbonyl-bis[5,7-di(propoxy)coumarin],3,3′-carbonyl-bis(7-methoxycoumarin),3,3′-carbonyl-bis(7-diethylamino-coumarin), 3-isobutyroylcoumarin,3-benzoyl-5,7-dimethoxy-coumarin, 3-benzoyl-5,7-diethoxy-coumarin,3-benzoyl-5,7-dibutoxycoumarin,3-benzoyl-5,7-di(methoxyethoxy)-coumarin,3-benzoyl-5,7-di(allyloxy)coumarin, 3-benzoyl-7-dimethylaminocoumarin,3-benzoyl-7-diethylaminocoumarin, 3-isobutyroyl-7-dimethylaminocoumarin,5,7-dimethoxy-3-(1-naphthoyl)-coumarin,5,7-diethoxy-3-(1-naphthoyl)-coumarin, 3-benzoylbenzo[f]coumarin,7-diethylamino-3-thienoylcoumarin,3-(4-cyanobenzoyl)-5,7-dimethoxycoumarin,3-(4-cyanobenzoyl)-5,7-dipropoxycoumarin,7-dimethylamino-3-phenylcoumarin, 7-diethylamino-3-phenylcoumarin, thecoumarin derivatives disclosed in JP 09-179299-A and JP 09-325209-A, forexample7-[{4-chloro-6-(diethylamino)-S-triazine-2-yl}amino]-3-phenylcoumarin;

4. 3-(aroylmethylene)-thiazolines

3-methyl-2-benzoylmethylene-□-naphthothiazoline,3-methyl-2-benzoylmethylene-benzothiazoline,3-ethyl-2-propionylmethylene-□-naphthothiazoline;

5. Rhodanines

4-dimethylaminobenzalrhodanine, 4-diethylaminobenzalrhodanine,3-ethyl-5-(3-octyl-2-benzothiazolinylidene)-rhodanine, the rhodaninederivatives, formulae [1], [2], [7], disclosed in JP 08-305019A;

6. Other Compounds

acetophenone, 3-methoxyacetophenone, 4-phenylacetophenone, benzil,4,4′-bis(dimethylamino)benzil, 2-acetylnaphthalene, 2-naphthaldehyde,dansyl acid derivatives, 9,10-anthraquinone, anthracene, pyrene,aminopyrene, perylene, phenanthrene, phenanthrenequinone, 9-fluorenone,dibenzosuberone, curcumin, xanthone, thiomichler's ketone,α-(4-dimethylaminobenzylidene) ketones, e.g.2,5-bis(4-diethylaminobenzylidene)cyclopentanone,2-(4-dimethylamino-benzylidene)-indan-1-one,3-(4-dimethylamino-phenyl)-1-indan-5-yl-propenone,3-phenylthiophthalimide, N-methyl-3,5-di(ethylthio)-phthalimide,N-methyl-3,5-di(ethylthio)phthalimide, phenothiazine,methylphenothiazine, amines, e.g. N-phenylglycine, ethyl4-dimethylaminobenzoate, butoxyethyl 4-dimethylaminobenzoate,4-dimethylaminoacetophenone, triethanolamine, methyldiethanolamine,dimethylaminoethanol, 2-(dimethylamino)ethyl benzoate,poly(propylenegylcol)-4-(dimethylamino) benzoate.

A photopolymerizable composition, comprising as further additive (d) aphotosensitizer compound selected from the group consisting ofbenzophenone and its derivatives, thioxanthone and its derivatives,anthraquinone and its derivatives, or coumarin derivatives is preferred.

The curing process can be assisted by adding photosensitizers, inparticular, in compositions which are pigmented (for example withtitanium dioxide), and also by adding a component which under thermalconditions forms free radicals, for example an azo compound such as2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), a triazene, diazosulfide, pentazadiene or a peroxy compound, for instance a hydroperoxideor peroxycarbonate, for example t-butyl hydroperoxide, as described forexample in EP 245639.

Other examples of component d) are colorants like pigments or dyes,which are inert towards the other components of the photoresistformulations and does not interfere with the photo polymerizationprocess. Example of such pigments and dyes include but not limited tophthalocyanines, Brilliant Green Dye, Malachite Green, fuchsine,auramine, Crystal Violet, Victoria Blue, substituted naphthalimide dyes,such as Calcofluor Yellow HEB, rhodamines and azosols.

In addition, the photopolymerizable mixtures may include variousadditives (d). Examples of these are thermal inhibitors, which areintended to prevent premature polymerization, examples beinghydroquinone, hydroquinone derivatives, p-methoxyphenol, β-naphthol orsterically hindered phenols, such as 2,6-di-tert-butyl-p-cresol In orderto increase the stability on storage in the dark it is possible, forexample, to use copper compounds, such as copper naphthenate, stearateor octoate, phosphorus compounds, for example triphenylphosphine,tributylphosphine, triethyl phosphite, triphenyl phosphite or tribenzylphosphite, quaternary ammonium compounds, for exampletetramethylammonium chloride or trimethylbenzylammonium chloride, orhydroxylamine derivatives, for example N-diethylhydroxylamine. Toexclude atmospheric oxygen during the polymerization it is possible toadd paraffin or similar wax-like substances which, being of inadequatesolubility in the polymer, migrate to the surface in the beginning ofpolymerization and form a transparent surface layer which prevents theingress of air. It is also possible to apply an oxygen-impermeable layeron top of the coating, for example poly(vinylalcohol-co-vinylacetate).Light stabilizers which can be added in a small quantity are UVabsorbers, for example those of the hydroxyphenylbenzotriazole,hydroxyphenyl-benzophenone, oxalamide or hydroxyphenyl-s-triazine type.These compounds can be used individually or in mixtures, with or withoutsterically hindered amines (HALS).

Examples of such UV absorbers and light stabilizers are

1. 2-(2′-hydroxyphenyl)benzotriazoles for example2-(2′-hydroxy-5′-methylphenyl)benzotriazole,2-(3′,5′-di-tert-butyl-2′-hydroxyphenyl)benzotriazole,2-(5′-tert-butyl-2′-hydro-xyphenyl)benzotriazole,2-(2′-hydroxy-5′-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole,2-(3′,5′-di-tert-butyl-2′-hydroxyphenyl)-5-chlorobenzotriazole,2-(3′-tert-butyl-2′-hydroxy-5′-methylphenyl)-5-chlorobenzotriazole,2-(3′-sec-butyl-5′-tert-butyl-2′-hydroxyphenyl)benzotrizole,2-(2′-hydroxy-4′-octoxyphenyl)benzotriazole,2-(3′,5′-di-tert-amyl-2′-hydroxyphenyl)benzotriazole,2-(3′,5′-bis-(α,α-dimethylbenzyl)-2′-hydroxyphenyl)-benzotriazole,mixture of2-(3′-tert-butyl-2′hydroxy-5′-(2-octyloxycarbonylethyl)phenyl)-5-chlorobenzotriazole,2-(3′-tert-butyl-5′-[2-(2-ethyl-hexyl-oxy)carbonylethyl]-2′-hydroxyphenyl)-5-chlorobenzotriazole,2-(3′-tert-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl)-5-chlorobenzotriazole,2-(3′-tert-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl)-benzotriazole,2-(3′-tert-butyl-2′-hydroxy-5′-(2-octyloxycarbonylethyl)phenyl)benzotriazole,2-(3′-tert-butyl-5′-[2-(2-ethylhexyloxy)carbonylethyl]-2′-hydroxyphenyl)benzotriazole,2-(3′-dodecyl-2′-hydroxy-5′-methylphenyl)benzotriazole, and2-(3′-tert-butyl-2′-hydroxy-5′-(2-isooctyloxycarbonylethyl)phenylbenzotriazole,2,2′-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-benzotriazol-2-yl-phenol];transesterification product of2-[3′-tert-butyl-5′-(2-methoxycarbonylethyl)-2′-hydroxy-phenyl]-benzotriazolewith polyethylene glycol 300; [R—CH₂CH₂—COO(CH₂)₃]₂— whereR=3′-tert-butyl-4′-hydroxy-5′-2H-benzotriazol-2-yl-phenyl.

2. 2-Hydroxybenzophenones, for example the 4-hydroxy 4-methoxy-,4-octoxy-, 4-decyloxy-, 4-dodecyloxy-, 4-benzyloxy-, 4,2′,4′-trihydroxy-and 2′-hydroxy-4,4′-dimethoxy derivative.

3. Esters of substituted or unsubstituted benzoicacids, for example4-tert-butylphenyl salicylate, phenyl salicylate, octylphenylsalicylate, dibenzoylresorcinol, bis(4-tert-butylbenzoyl)resorcinol,benzoylresorcinol, 2,4-di-tert-butylphenyl3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl3,5-di-tert-butyl-4-hydroxybenzoate, and2-methyl-4,6-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate.

4. Acrylates, for example isooctyl or ethyl α-cyano-β,β-diphenylacrylate, methyl α-carbomethoxycinnamate, butyl or methylα-cyano-β-methyl-p-methoxycinnamate, methylα-carboxymethoxy-p-methoxycinnamate andN-(β-carbomethoxy-β-cyanovinyl)-2-methylindoline.

5. Sterically hindered amines, for examplebis-(2,2,6,6-tetramethylpiperidyl) sebacate,bis-(2,2,6,6-tetramethylpiperidyl) succinate,bis-(1,2,2,6,6-pentamethylpiperidyl) sebacate,bis-(1,2,2,6,6-pentamethylpiperidyl)n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, condensation productof 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinicacid, condensation product ofN,N′-bis-(2,2,6,6-tetramethyl-4-piperidyl)hexa-methylenediamine and4-tert-octylamino-2,6-dichloro-1,3,5-s-triazine,tris-(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate,tetrakis-(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane tetraoate,1,1′-(1,2-ethandiyl)bis(3,3,5,5-tetramethyl-piperazinone),4-benzoyl-2,2,6,6-tetramethylpiperidine,4-stearyloxy-2,2,6,6-tetramethylpiperidine,bis-(1,2,2,6,6-pentamethylpiperidyl)2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl) malonate,3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro-[4.5]decane-2,4-dione,bis-(1-octyloxy-2,2,6,6-tetramethylpiperidyl) sebacate,bis-(1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, condensationproduct ofN,N′-bis-(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and4-morpholino-2,6-dichloro-1,3,5-triazine, condensation product of2-chloro-4,6-di-(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazineand 1,2-bis-(3-aminopropyl-amino)ethane, condensation product of2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazineand 1,2-bis-(3-aminopropylamino)ethane,8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione,3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidine-2,5-dione and3-dodecyl-1-(1,2,2,6,6-penta-methyl-4-piperidyl)-pyrrolidine-2,5-dione.

6. Oxalamides, for example 4,4′-dioctyloxyoxanilide,2,2′-diethoxyoxanilide, 2,2′-dioctyloxy-5,5′-di-tert-butyloxanilide,2,2′-didodecyloxy-5,5′di-tert-butyloxanilide,2-ethoxy-2′-ethyl-oxanilide, N,N′-bis-(3-dimethylaminopropyl)oxalamide,2-ethoxy-5-tert-butyl-2′-ethyloxanilide and its mixture with2-ethoxy-2′-ethyl-5,4′-di-tert-butyloxanilide, mixtures of o- andp-methoxy- and of o- and p-ethoxy-disubstituted oxanilides.

7. 2-(2-Hydroxyphenyl)-1.3.5-triazines, for example2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine,2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine,2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2,4-bis(2-hydroxy-4-propyloxy-phenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine,2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(4-methylphenyl)-1,3,5-triazine,2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-[2-hydroxy-4-(2-hydroxy-3-butyloxy-propyloxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-[2-hydroxy-4-(2-hydroxy-3-octyloxy-propyloxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-[4-dodecyl/tridecyl-oxy-(2-hydroxypropyl)oxy-2-hydroxy-phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine.

8. Phosphites and phosphonites, for example triphenyl phosphite,diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, distearylpentaerythrityl diphosphite, tris-(2,4-di-tert-butylphenyl) phosphite,diisodecyl pentaerythrityl diphosphite, bis-(2,4-di-tert-butylphenyl)pentaerythrityl diphosphite, bis-(2,6-di-tert-butyl-4-methylphenyl)pentaerythrityl diphosphite, bis-isodecyloxy pentaerythrityldiphosphite, bis-(2,4-di-tert-butyl-6-methylphenyl) pentaerythrityldiphosphite, bis-(2,4,6-tri-tert-butylphenyl) pentaerythrityldiphosphite, tristearyl sorbityl triphosphite,tetrakis-(2,4-di-tert-butylphenyl)-4,4′-biphenylene diphosphonite,6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-di-benzo[d,g]-1,3,2-dioxaphosphocine,6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzo[d,g]-1,3,2-dioxaphosphocine,bis-(2,4-di-tert-butyl-6-methylphenyl) methyl phosphite andbis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite.

To accelerate the photopolymerization it is possible to add amines ascomponent (d), for example triethanolamine, N-methyldiethanolamine,ethyl-p-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate,2-ethylhexyl-p-dimethylaminobenzoate,octyl-para-N,N-dimethylaminobenzoate,N-(2-hydroxyethyl)-N-methyl-para-toluidine or Michler's ketone. Theaction of the amines can be intensified by the addition of aromaticketones of the benzophenone type. Examples of amines which can be usedas oxygen scavengers are substituted N,N-dialkylanilines, as aredescribed in EP 339841. Other accelerators, coinitiators andautoxidizers are thiols, thioethers, disulfides, phosphonium salts,phosphine oxides or phosphines, as described, for example, in EP 438123,in GB 2180358 and in JP Kokai Hei 6-68309.

It is further possible to add chain transfer agents which are customaryin the art to the compositions according to the invention as component(d). Examples are mercaptans, amines and benzothiazol.

It is also possible to give a subject composition thermosetting propertyby adding compounds having epoxy groups as component (d). There may beused a solid or liquid known epoxy compound, and said epoxy compound isused depending on required characteristics. For example, when theplating resistance is to be improved, a liquid epoxy resin is used, andwhen water resistance is required, an epoxy resin having a large numberof methyl groups on a benzene ring or a cycloalkyl ring is employed. Apreferred epoxy resin, is a bisphenol S type epoxy resin such as BPS-200produced by Nippon Kayaku Co., Ltd., EPX-30 produced by ACR Co.,Epiculon EXA-1514 produced by Dainippon Ink & Chemicals Inc., etc.; abisphenol A type epoxy resin such as Epiculon N-3050, N-7050, N-9050produced by Dainippon Ink & Chemicals Inc., XAC-5005, GT-7004, 6484T,6099 produced by Ciba Specialty Chemicals. Inc., etc.; a bisphenol Ftype epoxy resin such as YDF-2004, YDF2007 produced by Tohto Kasei Co.,etc.; a diglycidyl phthalate resin such as Blemmer DGT produced byNippon Oil and Fats Co., Ltd., etc.; a heterocyclic epoxy resin such asTEPIC produced by Nissan Chemical Industries, Ltd., Araldite PT810produced by Ciba Specialty Chemicals Inc., etc.; a bixylenol type epoxyresin such as YX-4000 produced by Yuka Shell Co., etc.; a biphenol typeepoxy resin such as YL-6056 produced by Yuka Shell Co., etc.; atetraglycidyl xylenoylethane resin such as ZX-1063 produced by TohtoKasei Co., etc.; a novolak type epoxy resin such as EPPN-201, EOCN-103,EOCN-1020, EOCN-1025 and BRRN produced by Nippon Kayaku Co., Ltd.,ECN-278, ECN-292 and ECN-299 produced by Asahi Chemical Industry Co.,Ltd., GY-1180, ECN-1273 and ECN-1299 produced by Ciba SpecialtyChemicals Inc., YDCN-220L, YDCN-220HH, YDCN-702, YDCN-704, YDPN-601 andYDPN-602 produced by Tohto Kasel Co., Epiculon-673, N-680, N-695, N-770and N-775 produced by Dainippon Ink & Chemicals Inc., etc.; a novolaktype epoxy resin of bisphenol A such as EPX-8001, EPX-8002, EPPX-8060and EPPX-8061 produced by Asahi Chemical Industry Co., Ltd., EpiculonN-880 produced by Dainippon Ink & Chemicals Inc., etc.; a chelate typeepoxy resin such as EPX-49-69 and EPX-49-30 produced by Asahi DenkaKogyo K.K., etc.; a glyoxal type epoxy resin such as YDG-414 produced byTohto Kasei Co., etc.; an amino group-containing epoxy resin such asYH-1402 and ST-110 produced by Tohto Kasei Co., YL-931 and YL-933produced by Yuka Shell Co., etc.; a rubber-modified epoxy resin such asEpiculon TSR-601 produced by Dainippon Ink & Chemicals Inc., EPX-84-2and EPX-4061 produced by Asahi Denka Kogyo K.K., etc.; adicyclopentadiene phenolic type epoxy resin such as DCE-400 produced bySanyo-Kokusaku Pulp Co., Ltd., etc.; a silicone-modified epoxy resinsuch as X-1359 produced by Asahi Denka Kogyo K.K., etc.; an□-caprolactone-modified epoxy resin such as Plaque G-402 and G-710produced by Dicel Chemical Industries, Ltd., etc. and others. Further,partially esterified compounds of these epoxy compounds (e.g. esterifiedby (meth)acrylates) can be used in combination.

Further additives known in the art may be added as component (d), as forexample flow improvers, adhesion promoters, such asvinyltrimethoxysilane, vinyltriethoxysilanevinyltris(2-methoxyethoxy)silane,N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,N-(2-aminoethyl)3aminopropyltrimethoxysilane,3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane,3-glycidoxypropylmethyldimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane,3-methacryloxypropyltrimethoxysilane and3-mercaptopropyltrimethoxysilane. Surfactants, optical brighteners,pigments, dyes, wetting agents, levelling assistants, dispersants,aggregation preventers, antioxidants or fillers are further examples foradditives (d).

In order to cure thick and pigmented coatings it is appropriate to addglass microspheres or pulverized glass fibres, as described for examplein U.S. Pat. No. 5,013,768.

The choice of additive(s) (d) is made depending on the field ofapplication and on properties required for this field. The additivesdescribed above are customary in the art and accordingly are added inamounts which are usual in the respective application.

A polyester film or a polyethylene terephthalate film or other type ofplastic film is generally used as the support for the photopolymerizablecomposition of the invention.

The resin composition on the support is dried by heating.

The dried resist may be laminated with a protective film of polyethyleneor polypropylene if necessary.

The invention further relates to a dry film resist obtainable by theabove process.

Further Embodiment

To increase the intensity of the developed image a ‘latent acid’compound as disclosed in the PCT Publication WO02/101462, ApplicationNo. EP02/06105 or PCT Publication WO02/100914, application No.EP02/06109 can be added. Latent acids disclosed in the above PCTPublications are those of the formula

wherein

-   the ring A can contain one or more hetero atoms and/or can contain    an anelated ring, R₁ is hydrogen, alkyl, preferably C₁–C₂₀-alkyl,    alkenyl, preferably C₂–C₂₀-alkenyl, aryl, preferably phenyl or    phenyl which is substituted one to three times with C₁–C₄alkyl, or    C₁–C₄alkoxy,-   R₂, R₃, R₄ and R₅ independently of each other are hydrogen or a    functional substituent, and R stands for C₁–C₆alkyl, -Z₁-Q₁, or    -Z₂Q₂,    wherein Z₁ is a single bond, S, NH or O, and Q₁ is a heterocyclic    ring system having from 5 to 9 ring atoms selected from C, S, O and    N, with at least 2, preferably at least 3, more preferably at least    4 carbon atoms in the ring system, preferably Q₁ stands for    morpholine, pyridine, which may be substituted one to three times    with C₁–C₄alkyl or hydroxy, mercaptobenzoxazole,    mercaptobenzthiazole,    and wherein Z₂ stands for C₁–C₄alkylene, which can be substituted by    C₁–C₄alkyl or Q₃, wherein Q₃ stands for phenyl which can be    substituted one to three times with C₁–C₄alkyl, hydroxy,    C₅–C₈cycloalkyl and/or a heterocyclic ring system having from 5 to 9    ring atoms selected from C, S, O and N, with at least 2, preferably    at least 3, more preferably at least 4 carbon atoms in the ring    system, and Q₂ stands for phenyl which can be substituted one to    three times with C₁–C₄alkyl, hydroxy, C₅–C₈cycloalkyl and/or a    heterocyclic ring system having from 5 to 9 ring atoms selected from    C, S, O and N, with at least 2, preferably at least 3, more    preferably at least 4 carbon atoms in the ring system, with the    proviso that the hydrogen atom at the C-atom in a-position to R can    be split off by irradiation.

Preferably, Z₂ stands for —CH₂—, —CH₂—CH₂—, —CH₂—CHMe—, —CH₂—CHQ₃-, inwhich Q₃ stands for 4-hydroxy-3-1-propyl-6-methylphenyl,4-hydroxy-3-tert.-butyl-6-methylphenyl, or4-hydroxy-3-cyclohexyl-6-methylphenyl and Q₂ stands for phenyl or4-hydroxy-3-1-propyl-6-methylphenyl,4-hydroxy-3-tert.-butyl-6-methylphenyl, or4-hydroxy-3-cyclohexyl-6-methylphenyl.

Suitable rings A are e.g. phenyl, naphthyl, pyridyl and quinolinyl,phenyl and pyridyl are especially preferred.

R₁ is preferably hydrogen, or methyl.

Functional substituents R₂, R₃, R₄ and R₅ are e.g. C₁–C₂α-alkyl,preferably C₁–C₈-alkyl, particularly preferred C₁–C₆-alkyl, especiallypreferred C₁–C₄-alkyl, C₅–C₈-Cycloalkyl, C₂–C₂₀-alkenyl, preferredC₂–C₆-alkenyl, C₁–C₆-alkoxy, hydroxy, halogen, nitro, cyano, —SO₂R′,wherein R′ is hydrogen, alkyl or a metallic cation such as a alkalimetal, e.g. sodium or potassium, or earth alkali metal cation, e.g.calcium, or phenyl, which may be substituted one to three times withhydroxy and/or Z₂₁-R₇, wherein Z₂₁ stands for C₁–C₄alkylene, which canbe substituted by C₁–C₄alkyl, and R₇ stands for hydrogen, C₁–C₄alkyl orphenyl, which may be substituted one to three times with hydroxy,C₁–C₄alkyl and/or Z₂₂-R₈, wherein Z₂₂ stands for for C₁–C₄alkylene,which can be substituted by C₁–C₄alkyl, and R₈ stands for a heterocyclicring system having from 5 to 9 ring atoms selected from C, S, O and N,with at least 2, preferably at least 3, more preferably at least 4carbon atoms in the ring system, preferably R₈ stands for morpholine. Ina preferred embodiment of this invention R₂, R₃, R₄ and R₅ arepreferably independently of each other hydrogen, C₁–C₂₀-alkyl orC₂–C₂₀-alkenyl or substituted phenyl wherein hydroxy and Z₂₁-R₇ beingthe substituents. Especially preferred compounds of formula (1) arethose wherein R₂ and R₃ are independently of each other C₁–C₈-alkyl andR₄ and R₅ are each hydrogen.

Especially suitable latent acids are:

Compound (13) is commercially available from Aldrich CAS number[1843-03-4] 1,1,3-Tris(2-methyl-4-hydroxy-5-tert.butylphenyl)butane.

Another suitable latent acid is a phenolic antioxidant such aspentaerythritol tetrakis (3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (available as Irganoxe® 1010, Ciba Specialty Chemicals).

Colour formers can be formulated with these latent acids in plastics viamelt processing to produce an essentially colourless heat stablesubstrate that can be selectively imaged by exposure to UV light of acertain wavelength and intensity. The latent acids are normally used ina ratio of 0.1–10 parts per 1 part colour former.

Preferred is a 1:1 mixture of compound (13) with Pergascript Blue SRB.

Preparation:

a) Preparation of the Dye.

The dye according to point (e) is commercially available, for examplePergascript Blue S-RBP from Ciba Specialty Chemicals or can be preparedaccording to methods known in the art such as those disclosed in U.S.Pat. No. 4,154,463 manufacturing direction J.

b) Preparation of the Photocurable Resin Composition.

The method for preparing the photocurable resin composition of thepresent invention is not limited to any special method, and can beprepared by a conventional mechanical mixing process.

The compositions may be used as a solution prepared by dissolving theingredients (a) to (e) in an appropriate solvent. Such solvents includesolvents for use in conventional resist compositions, such as acetone,methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone,and other ketones; ethylene glycol, propylene glycol, diethylene glycol,ethylene glycol monoacetate, propylene glycol monoacetate, diethyleneglycol monoacetate, or their monomethyl ethers, monoethyl ethers,monopropyl ethers, monobutyl ethers or monophenyl ethers, and otherpolyhydric alcohols and derivatives thereof; dioxane, and other cyclicethers; and ethyl lactate, methyl acetate, ethyl acetate, butyl acetate,methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethylethoxypropionate, and other esters. Each of these solvents can be usedalone or in combination.

c) Preparation of a Resist Element and Way to Use a Dry Film Resist.

The process for preparing a dry film resist element comprises the stepsof

-   (A) forming a photocurable resin composition layer made of    ingredients(a)–(e) as defined above onto a support film with a    thickness of 1 to 50 μm, and laminate a protective film onto the    photocurable composition layer to obtain a dry film resist;-   (B) removing the protective film before use, and thermally laminate    the photocurable composition layer onto the surface of a desired    substrate for the application of the dry film resist at 100–150° C.;-   (C) exposure to radiation through a mask or by direct laser    irradiation;-   (D) removing the support film and wash away the unexposed (uncured)    area by development.

Radiation sources which can be used are in principle all lamps whichemit radiation in the UV and/or VIS region. Both point light sources andspread emitters (lamp carpets) are suitable. Examples are: carbon arclamps, xenon arc lamps, mercury vapour lamps, if desired doped withmetal halides (metal halide lamps), fluorescent lamps, argonincandescent lamps, electronic flash lamps, photographic flood lamps,electron beams and X-rays. Laser lights can also be used as a source,for example argon ion lasers, krypton ion lasers, argon ion UV laser(DP-100 from Orbotech) solid state UV laser (Gemini from ManiaBarco,DI-2050 from PENTAX) and violet laser (405 nm; DI-2080 and DI-PDP fromPENTAX). Laser light also allows the resist to be exposed without a maskby writing the controlled laser beam directly on the resist layer.

Use

Application areas of the dry film resist element using thephotosensitive composition described in the present invention are forforming copper circuit pattern of printed circuit board and LSIpackaging like etching resist and plating resist, for solder resist andfor forming cell or electrode pattern in various flat display panelapplications, e.g. forming barrier lib used in a plasma display panel bysand blast method.

EXAMPLES Example 1

Sample Preparation

A photocurable resist formulation for a dry film resist is prepared bymixing 100 parts by weight of ACA200M [solid content is 50% in weight](Daicel Chemical Industries, Ltd.), 20 parts by weight ofdipentaerythritol hexaacrylate (Aldrich), 3.5 parts by weight of(4-morpholinobenzoyl)-1-benzyl-1-dimethylaminopropane (IRGACURE369 fromCiba Specialty Chemicals) and 50 parts by weight of acetone. To thatmixture 0.6 parts by weight of4,4′-[(9-Butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline](Pergascript Blue S-RBP from Ciba Specialty Chemicals) is added andstirred. All operations are carried out under yellow light. Theformulations are applied to PET film. The solvent is removed by heatingat 80° C. for 10 minutes in a convection oven. The thickness of thedried resist layer is 33 μm.

Evaluation

The color generation of the resist are monitored by the visibleabsorption at 620 nm by using spectrophotometer U-3300 (Hitachi). Afterthe measuring absorbance, the resist surface is laminated with PET andheated at 130° C. for 15 minutes to mimic the heat lamination step of adry film resist process. Then the absorbance is measured after removingthe PET film from the one side of the resist. The resist is exposed at300 mJ/cm² by using a metal halide lamp (ORC, model SMX 3000), and theabsorbance is measured.

Comparative Example

Sample preparation and evaluation are done in the same way as Exampleexcept4,4′-[(9-Butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline]is replaced with 0.3 parts by weight of Leuco Crystal Violet (Aldrich).

The results are shown in Table 1.

Absorbance Example Treatment at 620 nm Example 1 before treatment 0 15min. 130° C. 0.005 15 min. 130° C. + 300 mJ/sqcm 0.065 Comparative Ex.before treatment 0 15 min. 130° C. 0.03 15 min. 130° C. + 300 mJ/sqcm0.062

The Examples clearly show that using a leuco dye described by thegeneral formula I, unfavourable colour generation during the heatlamination process is reduced and enough color generation can beachieved after UV exposure. Thus clear color contrast between exposedand unexposed area is obtained.

Example 2

Sample Preparation

A photocurable resist formulation for a dry film resist is prepared bymixing 50 parts by weight of esterified styrene maleic-anhydridecopolymer (Scripset 540 from Hercules), 50 parts by weight oftrimethylolpropane triacrylate (TCI), 5.0 parts by weight of2,2-dimethoxy-2-phenyl acetophenone (IRGACURE651 from Ciba SpecialtyChemicals), 130 parts by weight of acetone and 20 parts by weight ofmethanol. To that mixture 0.5 parts by weight of4,4′-[(9-Butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline](Pergascript Blue S-RBP from Ciba Specialty Chemicals) is added andstirred. All operations are carried out under yellow light. Theformulations are applied to PET film. The solvent is removed by heatingat 60° C. for 10 minutes in a convection oven. The thickness of thedried resist layer is 38 μm.

Evaluation

The color generation of the resist is monitored by the visibleabsorption at 620 nm by using spectrophotometer U-3300 (Hitachi). Theabsorption is measured before and after the heat treatment at 100° C.for 5 minutes to mimic the heat lamination step of a dry film resistprocess. Then the resist is exposed at 50 mJ/cm² by using a metal halidelamp (ORC, model SMX 3000), and the absorbance is measured.

Comparative Example 2

Sample preparation and evaluation are done in the same way as Example 2except4,4′-[(9-Butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline]is replaced with 0.5 parts by weight of Leuco Crystal Violet (Aldrich).

The results are shown in Table 2.

Absorbance Example Treatment at 620 nm Example 2 before treatment 0.0205 min. 100° C. 0.042 5 min. 100° C. + 50 mJ/sqcm 0.155 Comparative Ex. 2before treatment 0.034 5 min. 100° C. 0.137 5 min. 100° C. + 50 mJ/sqcm0.176

Example 3-1

Sample Preparation

A photocurable resist formulation for a dry film resist is prepared bymixing 70 parts by weight of esterified styrene maleic-anhydridecopolymer (Scripset 540 from Hercules), 30 parts by weight oftrimethylolpropane triacrylate (TCI), 5.0 parts by weight of(4-morpholinobenzoyl)-1-benzyl-1-dimethylaminopropane (IRGACURE369 fromCiba Specialty Chemicals), 130 parts by weight of acetone and 20 partsby weight of methanol. To that mixture 1.0 parts by weight of4,4′-[(9-Butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline](Pergascript Blue S-RBP from Ciba Specialty Chemicals) is added andstirred (s-1). All operations are carried out under yellow light. Theformulations are applied to PET film. The solvent is removed by heatingat 60° C. for 10 minutes in a convection oven. The thickness of thedried resist layer is 38 μm.

Evaluation

The color generation of the resist are monitored by the visibleabsorption at 620 nm by using spectrophotometer U-3300 (Hitachi). Theabsorption is measured before and after the heat treatment at 100° C.for 5 minutes to mimic the heat lamination step of a dry film resistprocess. Then the resist is exposed at 400 mJ/cm² by using a metalhalide lamp (ORC, model SMX 3000), and the absorbance is measured.

Example 3-2

Sample preparation and evaluation are done in the same way as Example3-1 except 2.0 parts of Irgacure 250 (iodonium,(4-methylphenyl)[4-(2-methylpropyl)phenyl]-, hexafluorophosphate(1-) byCiba Specialty Chemicals) is added to the resist solution (s-1).

Comparative Example 3

Sample preparation and evaluation are done in the same way as Example3-1 except4,4′-[(9-Butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylaniline]is replaced with 0.5 parts by weight of Leuco Crystal Violet (Aldrich).

The results are shown in Table 3.

TABLE 3 Absorbance Example Treatment at 620 nm Example 3-1 beforetreatment 0.012 5 min. 100° C. 0.032 5 min. 100° C. + 400 mJ/sqcm 0.077Example 3-2 before treatment 0.012 5 min. 100° C. 0.029 5 min. 100° C. +400 mJ/sqcm 0.109 Comparative Ex. 3 before treatment 0.018 5 min. 100°C. 0.061 5 min. 100° C. + 400 mJ/sqcm 0.106

The Examples clearly show that using a leuco dye described by thegeneral formula I, unfavorable color generation during the heatlamination process is reduced and enough color generation can beachieved after UV exposure. By adding iodonium photo acid generator,Irgacure 250, into the formulation the color generation of a leuco dyedescribed by the general formula I is promoted with retaining the lowlevel of color generation during the heat lamination process. Thus clearcolor contrast between exposed and unexposed area is obtained.

1. A process for preparing a dry film resist, which process comprisesforming a photocurable resin composition onto a support film with athickness of 1 to 50 μm and optionally laminate a protective film ontothe photocurable composition layer to obtain a dry film resist; wherebythe photocurable resin is formed from a homogeneous mixture comprising(a) from 20–90 wt % of an alkaline soluble acrylic polymer havingcarboxylic acid function as a pendant group and having a molecularweight of about 2,000 to 2,000,000, and an acid value from 50 to 600 mgKOH/g; (b) from 5 to 60 wt % of one or more photopolymerizable monomerswhich are compatible with the oligomers and polymers of component (a);(c) from 0.01 to 20% by weight of one or more photoinitiators; (d) from0 to 20% by weight of additives and/or assistants; and (e) from 0.1 to10% by weight of a leuco triphenylmethane dye of the formula I

wherein R¹ is a residue selected from

R² is C₁–C₁₂ alkyl or phenyl which may be mono-, di- or tri-substitutedby C₁–C₆ alkyl, trifluoromethyl, C₁₋₆ alkoxy, C₁₋₆ alkylthio, halogenand nitro; R³ is hydrogen or C₁–C₁₂ alkyl; R⁴ to R⁹ independently of oneanother are hydrogen or C₁–C₁₂ alkyl; and X is O, S, NH orN—C₁–C₁₂-alkyl; where the total of (a) through (e) equals 100% byweight.
 2. A process according to claim 1, wherein in formula I R¹ is aresidue

R² is unsubstituted phenyl, R³ is C₁–C₄alkyl R⁴ is hydrogen; and R⁵ andR⁷ are C₁–C₄alkyl.
 3. A process according to claim 1, wherein the leucotriphenylmethan dye is4,4′-[(9-Butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylanilineof the formula


4. A process according to claim 1, wherein component d) includes adiaryliodonium of formula.

wherein X is branched C₃–C₂₀alkyl or C₃–C₈cycloalkyl; X₁ is hydrogen,linear C₁–C₂₀alkyl, branched C₃–C₂₀alkyl or C₃–C₈cycloalkyl; with theproviso that the sum of the carbon atoms in X and X₁ is at least 4; Y islinear C₁–C₁₀alkyl, branched C₃–C₁₀alkyl or C₃–C₈cycloalkyl; A⁻ is anon-nucleophilic anion, selected from the group consisting of (BF₄)⁻,(SbF₆)⁻, (PF₆)⁻, (B(C₆F₅))₄ ⁻, C₁–C₂₀alkylsulfonate,C₂–C₂₀haloalkylsulfonate, unsubstituted C₆–C₁₀arylsulfonate,camphor-sulfonate, C₁–C₂₀-perfluoroalkylsulfonylmethide,C₁–C₂₀-perfluoroalkylsulfonylimide, and C₆–C₁₀arylsulfonate substitutedby halogen, NO₂, C₁–C₁₂alkyl, C₁–C₁₂halo-alkyl, C₁–C₁₂alkoxy or byCOOR₁; and R₁ is C₁–C₂₀alkyl, phenyl, benzyl; or phenyl mono- orpoly-substituted by C₁–C₁₂alkyl, C₁–C₁₂alkoxy or by halogen.
 5. A dryfilm resist obtained by a process according to claim
 1. 6. A process forpreparing a dry film resist element comprising the steps of (A) forminga photocurable resin composition layer made of ingredients (a)–(e)according to claim 1 onto a support film with a thickness of 1 to 50 μm,and laminate a protective film onto the photocurable composition layerto obtain a dry film resist; (B) removing the protective film beforeuse, and thermally laminate the photocurable composition layer onto thesurface of a desired substrate for the application of the dry filmresist at 100–150° C.; (C) exposure to radiation through a mask or bydirect laser irradiation; and (D) removing the support film and washaway the unexposed (uncured) area by development.
 7. A dry film resistelement obtained by a process according to claim
 6. 8. A processaccording to claim 6 wherein component (e) is4,4′-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N-phenylanilineof the formula


9. A process according to claim 6 for forming copper circuit pattern ofprinted circuit boards, LSI packaging etching resist or plating resist,for solder resist or for forming cell or electrode pattern in flatdisplay panel applications.